Some asphalt mixes have been proposed in the past, which include new aggregate and new asphalt, and are suitable for paving at ambient temperatures. Typically, the new aggregate is heated, and heated new asphalt is added to produce a heated asphalt composition. Alternatively, a mixture of new aggregate and recycled aggregate, which is obtained from crushing recycled asphalt concrete, has been used, and heated asphalt is added to produce a heated asphalt composition. To these heated asphalt compositions, a suitable amount of volatile oil, such as heavy oil, light oil, or kerosene, is added to soften the asphalt, so that the resulting asphalt mix will not congeal and solidify immediately after returning to an ambient temperature.
These asphalt mixes are environmentally disadvantageous in that the volatile oil included in these mixes starts to evaporate and is emitted to ambient air immediately after the mixes are applied to form a pavement. Further, these mixes cannot harden immediately after their application at a paving site and, rather, take a considerable amount of time before achieving a desired hardness. The amount of volatile oil to be added may be reduced so as to achieve a sufficiently hard pavement surface immediately after paving. This, however, will make it impossible to store the asphalt mix for a long period since a reduced amount of volatile oil will almost entirely evaporate while in storage, thereby causing the asphalt mix to solidify.
Some other asphalt mixes have been proposed in the past, which include a special additive (chemical substance) to cause a polycondensation reaction, so as to increase the hardness of the resulting asphalt pavement after it is solidified. Production of such special additives, however, is extremely cumbersome and expensive, and the strength of the resulting asphalt pavement cannot be expected to improve substantially.
To overcome these disadvantages described above, some asphalt mixes using only recycled aggregate obtained from crushing recycled asphalt concrete have been proposed, which are also suited for application at ambient temperatures. These mixes include practically nonvolatile additive oil, such as petroleum hydrocarbons. Though this type of asphalt mix overcomes some disadvantages associated with other mixes described above, it still suffers some disadvantages.
Specifically, since recycled asphalt concrete used in this type of mix is obtained by peeling off a roadbed surface, the quality of recycled asphalt concrete tends to vary and, often, is poor. When poor quality recycled asphalt concrete is used to form an asphalt mix, the mix may not be suited to form a sufficiently strong and stable pavement. Further, recycled asphalt concrete is often excessively oxidized and becomes as stiff as a cement pavement material and, thus, may lack elasticity required to form a suitable asphalt pavement material.
A need exists for an improved asphalt mix suitable for forming and repairing a pavement at an ambient temperature, which can be stored for a long time, and is capable of achieving sufficient strength and stability immediately after its application at a paving site. Such asphalt mix preferably should also be environmentally friendly. Further, the quality of such asphalt mix preferably should not depend solely on the quality of recycled asphalt concrete, which often tends to be poor.